Field of the Invention
The present invention relates to a device for detecting air flows including an air line channeling the air flow. The air line includes at least one first temperature sensor and one second temperature sensor.
There are a range of devices available that are designed to detect the presence of an air flow or to measure an air flow or fluid flow in a line, such as a smoke/heat exhaust line.
In particular, it is known that it is possible to detect an air flow in a line channeling said flow using at least one temperature sensor, such as a resistive NTC temperature sensor.
Such a system is described in document FR2983950A1, the introduction to which describes a device referred to as a “thermal flow meter” for detecting the flow of a fluid in a line (such as the admission inlet of a heating device), said line including at least a first temperature sensor and a second temperature sensor (both resistive NTC temperature sensors) immersed in the fluid. One of the sensors is used to measure the temperature of the incoming fluid, and the other sensor is powered by an electrical current of known intensity, such that the temperature of same is raised above the temperature of the fluid to be measured/detected. The same document then describes an advantageous positioning solution for said sensors at a given incline in relation to a main axis of the air line or fluid line to ensure that dirt does not hinder detection of the air flow.
Depending on the choice of electrically powered temperature sensor (or heat sensor), the device for detecting air flows may require a suitable electricity supply, and consequently the energy consumption of the two sensors is quite significant. The operating cost of the device for detecting air flows is therefore also quite significant. These drawbacks make use of such a device for detecting air flows particularly unsuited for more demanding line environments, such as in onboard systems (trains, planes, etc.) or in complex infrastructure (buildings, factories, etc.).
Finally, for safety reasons, it is essential that the device for detecting air flows including at least one temperature sensor powered by an electrical current to raise the temperature of same to a given level (as in document FR2983950A1) can be checked to determine whether said sensor is subject to ageing or has suffered a failure. This also applies to the second sensor (as in document FR2983950A1) used to measure the temperature of the incoming fluid. This diagnostic check should also be cheap and draw little power. This would improve assessment of the precision of air flow detection, in particular for safety applications (for example in relation to ventilation lines used in connection with smoke/fire hazards).